MC= Uke
ML= Seme
Mc fell into that blackhole thingy(cannot remember the actual term but it's the thing that makes a person end up at the Atlantic Ocean. Remember the unpredictable blackhole. That's what I call it) that was in the dungeon that they were inspecting, causing him to time-travel to ML when he was a kid, that's how they met. Hence, ML remembers being rescued by his hyung also MC hid his name because he didn't want any weird butterfly effect so that's why ML didn't know MC was ML hell MC didn't even know he was the hyung not until he had time travel and was in bad shape.
ML - Seme
MC - Uke
imprinting
ML didn't imprint on the current MC he did the imprint on MC when they were in the past. Alright, let me see if i can explain it. I'm a be honest, i suck at explaining so...
MC right now didn't get an imprint on him. When MC fell into the weird blackhole, his now self had gone back into the past. ok, u following *(idk how old MC i forgot, so i will say he 18). Present MC 18 when he went back to the past, he was the present age 18 before he went back to the past. No imprint was on him, but after he returned to the present, he got the imprint on him. Remember ML imprint on his hyung as in the 18-year-old MC . As for the imprint not working on MC right now is because he hasn't gone back to the past, hence why it's reading MC as a stranger guide. It's fucking complicated, but the novel explains it better than I do u know, the infinity sign it's fucking like that. Also don't ask for cp number cause i really can't remember.

So it's almost certain that he is woojoo hyung?